Most listings are in the $10's per square foot per year. The Iowa City submarket is going through a a boost in rates. In the last 3 months, the median rate rose $19 per sqft per year.
In the last 90 days, 24 listings have been posted online, which means listings are probably leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 33% of the office spaces in the Iowa City are subleases, so you might be able to sign a shorter term by taking over a previous lease. There aren't many listings below 2,000 square feet posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,190 sqft. Most properties in this area are close to 2 floors. Most buildings in this area were built in 1989 and are Class A.